Process for the polymerization of olefins to high molecular weight substances



-Oct. 27, 1942. Q SKQOGLUND 2,300,069

PROCESS FOR THE POLYMERIZATION OF OLEFINS TO HIGH MOLECULAR WEIGHTSUBSTANCES Filed June 17, 1939 VAPOR OUTLET CATALYST INLET POLYME'I?'PROJDOCF IRA WOFF M 0 buff Patented Oct. 27, 1942 PROCESS FOR THEPOLYMEBIZATION F OLEFINS TO HIGH MOLECULAR WEIGHT SUBSTANCES Arthur 0.Skooglund, Clark Township, Union County, N. 1., assignor, by mesneassignments, to Jasco, Incorporated, a corporation of DelawareApplication June 17, 1939, Serial No. 279,665

8 Claims. (Cl. 260-94) This invention relates to synthetic polymermaterials having a'high molecular weight, and

relates particularly to a polymerized isooleflnic substance, and to themethod of production, utilizing a catalyst aid to increase the polymericmolecular weight.

It has been found that the isooleflnic substances such as isobutylenewhen treated at low temperatures ranging from 0' C. to l00 C. with apolymerization catalyst of the type of boron tzifluoride are polymerizedinto solid, plastic, elastic materials which are valuable for manypurposes such as cable insulation, lacquers, etc. In the production ofthese materials it is found that the lower the temperature ofpolymerization and the purer the oleflnic material, the higher themolecular weight. Under such suitable circumstances the molecular weightof the polymer may be brought to' values ranging from 50,000 to 250,000depending to a considerable extent upon the purity, and lowness of thetemperature. However, these very low temperatures are somewhat expensiveand diiilcult to obtain, and maximum purity of the isobutylene,especially freedom from acidic matter,

The present invention provides a simple addition agent which is capableof increasing materially the molecular weight of polymer obtainable bypolymerization at a given temperature and from a given purity ofmaterials. This polymerization improving agent may conveniently take theform of an organlc sulfide such as carbon dlsulflde, or a phenolicsulfide or an aryl sulfide or an alkyl sulfide, which when added to thepolymerization mixture of less purity in small proportions at less lowtemperatures is found to increase the molecular weight of the resultingpolymer by from 10% to 50% without the need of ultra purity or ultra lowtemperature and without any reduction in the yield of polymer or anyincrease in the catalyst consumption. Thus an obiectof the invention isto improve and suppletitles of gasoline boiling range hydrocarbons. Thecracking operation yields approximately 15% of gaseous by-productcomposed in large part of a mixture of hydrogen, methane and itshomologues, ethylene and its homologues, etc.. including isobutylene.'I'he isobutylene is separated from the gas mixture and forms one of theraw materials for the polymerization reaction.

The isobutylene is cooled to a temperature ranging from 0 C. to -l00 0.,preferably to temperatures between -50 C. and -'l5 C. It is preferablymixed with a diluent-refrigerant such as liquid ethylene, or liquidpropane with solid C02, and then treated with boron trifluoride-as apolymerization catalyst. The addition of the boron trifluoride producesa rapid polymerization reaction which converts the normally gaseousisobutylene into a normally solid, plastic, elastic substance which, incontrast to the highly chemically unsaturatedisobutylene from which itwas prgduced, is a substantially chemically saturated sol d.

With reasonably pure iscbutylene in the proportion of 1 part to 1% to 4parts of solid carbon dioxide, and ,5000 to A000 Part of borontrifluorlde as catalyst at a temperature of approximately '70 C., theresulting polymer usually has a molecular weight of from 60,000 to80,000.

tion, The addition of the carbon disulfide does ment the effect of apolymerization catalyst in the not result in any reduction in yield nordoes it require the use of any additional quantities of the borontriiiuoride catalyst.

It should be noted that the sulfide used should be of good purity, sincemany sulfur compounds are very poisonous to the polymerization reaction.This is especially true of hydrogen sulfide, which, being an acid typeof compound, is particularly harmful to the polymerization reaction, andgreatly reduces the molecular weight of polymer obtained. The metallicsulfides are also very harmful, but the insolubility in organicsolvents, and at low temperatures, reduces the harm caused by theirpresence. The mercaptans are also harmful, probably because of thepresence of a labile hydrogen atom, analogous to the hydrogen ofhydrogen sulfide.

In contrast, the organic sulfides, generally, and especially those whichdo not have a labile hydrogen, are useful as polymerization aids, asabove pointed out, the exact utility and efliciency being dependent inlarge extent on other features of the compound. The more usefulcompounds of this type are the phenolic sulfides, aryl sulfides; andalkyl sulfides.

The catalyst aid may be left in the polymer after the completion of thepolymerization reaction, especially the carbon disulfide, since it isfound that this compound is of great value as a stabilizer in thefinished polymer, and when so present very substantially increases theresistance of the polymer to breakdown and to depolymerization fromheating and from mechanical working such as milling, as well as otherdestructive forces.

The same reaction applies to mixtures of isoolefins and diolefins, andto other catalysts such as aluminum chloride, especially aluminumchloride dissolved in ethyl or methyl chloride, as well as to thevarious other polymerization catalysts such as titanium tetrachloride,silicon tetrachloride, zinc chloride, germanium chloride, etc., eitherdissolved directly in the reaction mixture, or in solution in otherorganic halides.

By the process of the invention there is thus provided asimple,'i'nexpensive and efficient step for increasing the molecularweight of the isoolefin polymer substance.

A diagrammatic elevational view of an apparatus suitable for carryingout the process of the present invention as illustrated in theaccompanying drawing wherein l is a reactor into which is fed aliquefied olefinic reactant from inlet 2, a liquid diluent, e. g.,liquefied ethylene, from inlet 3, a Friedel-Crafts type catalyst, e. g.,boron fluoride, from inlet 4, and a proportioned amount of the carbondisulfide promoter from inlet 5. A draw-oil line 6 may be provided toremove the polymer product from the reactor. Diluent may be recoveredfor reuse by leading vapors from the reactor by way of line 8 thru apressure control valve 9, then purifying the diluent vapors to thedesired extent before they are liquefied and recycled. The reactor maybe equipped with a mechanical stirrer l0.

While there are above disclosed but a limited number of embodiments ofthe device of the invention, it is possible to produce still otherembodiments without departing from the inventive concepts hereindisclosed and it is therefore desired that only such limitations beimposed on the appended claims as are stated therein or re uired by theprior art.

-The invention claimed is:

1. A process for polymerizing olefinic bodies comprising the steps ofcondensing an olefinic substance containing isobutylene to av liquid,

diluting the condensed olefin with a diluent-' refrigerant comprisingliquid ethylene at a temperature below 0., adding a catalyst aid theretocomprising carbon disulfide, and polymerizing the material to a highmolecular weight polymer by the application to the mixture of a Friedel-Crafts type catalyst comprising boron trifluoride the said catalyst aidbeing present in the ratio of 0.05% to 2% of the iso-olefin.

2. A process for polymerizing olefinic bodies comprising the steps ofcondensing an olefinic substance containing isobutylene to a liquid,diluting the condensed olefin with a diluentrefrigerant comprisingliquid ethylene at a temperature below 0 0., adding a catalyst aidthereto comprising carbon disulfide, and polymerizing the material to ahigh molecular weight polymer by the application to the mixture of aFriedel- Crafts type catalyst comprising aluminum chloride dissolved inmethyl chloride.

3. The method of producing an olefinic polymer substance of highmolecular weight comprising the steps of condensing an impureolefincontaining gas to a liquid, cooling the liquid to a moderately lowtemperature below 0 C., dissolving therein a catalyst aid comprisingcarbon disulfide, and treating the mixture with a Friedel-Crafts typecatalyst comprising boron trifluoride.

4. The method of producing an olefinic polymer substance of highmolecular weight comprising the steps of condensing an impureolefincontaining gas to a liquid, cooling the liquid to a moderately lowtemperature of approximately 40 C., dissolving therein a catalyst aidcomprising carbon disulfide, and treating the mixture with aFriedel-Crafts type catalyst comprising boron trifiuoride.

5. The method of producing an olefinic polymer substance of highmolecular weight comprising the steps of condensing an olefinic gas to aliquid, cooling the liquid to a low temperature below approximately 0C., dissolving therein a catalyst aid comprising carbon disulfide in aproportion ranging between 0.05% and 2% of the olefin and treating themixture with a Friedel-Crafts type catalyst in the proportion of 0.1% to0.5% of the olefinic material.

6. In a process for polymerizing olefinic substances including the stepsof condensing the olefinic substances to a liquid at a temperature below0 C. and polymerizing the condensed liquid by the addition of aFriedel-Crafts type catalyst thereto, the new step of reinforcing thecatalyst by the addition of carbon disulfide.

7. Process of polymerizing olefinic hydrocarbons including an iso-olefinreactant at low temperatures below 0 C. comprising the steps of addingto the said hydrocarbons carbon disulfide in a small proportionsuflicient to promote the polymerization reaction, and polymerizing saidreactant in liquid phase with the aid of a Friedel-Craits type catalyst.

8. A polymerization mixture comprising a high molecular weightiso-olefin polymerization productand a small proportion of carbondisulfide sufllcient to stabilize said product.

ARTHUR C. SKOOGLUND.

